Resettable downhole torque limiter and related methods of use

ABSTRACT

Disclosed is a torque limiter having driver mandrel and driven axially aligned mandrels, a piston movable into and out of an engaged position wherein the driver and driven mandrels are coupled together to transmit torque there between. Hydraulically locking the movable piston in an engaged position. Disengaging the hydraulic lock when during rotation when a specified torque magnitude is exceeded to allow relative rotation between the mandrels. Resetting the torque limiter by hydraulically locking the piston in the engaging position when relative rotation ceases or is reduced.

CROSS REFERENCE TO RELATED APPLICATIONS

This patent application is a divisional of U.S. application Ser. No.13/051,813, filed Mar. 18, 2011, which claims priority to U.S.Provisional Patent Application No. 61/315,598, filed Mar. 19, 2010,which is hereby incorporated by reference in its entirety.

BACKGROUND Technical Field

This invention relates, generally, to apparatus and methods used in wellservicing, such as oil and gas wells. More specifically, this inventionrelates to apparatus which joins two downhole elements together in atubing string and limits the torque transmitted from one element toanother.

SUMMARY OF THE INVENTIONS

A common problem encountered in drilling and servicing hydrocarbon wellsis found when using an assembly of pipe sections which steps down indiameter to extend into a relatively smaller diameter borehole below thelarger main casing section. In, for example, a “drillstring,” thereduced diameter drillpipe and their threaded connections have lowertorque specifications than the larger diameter drillpipe it is connectedto. It is therefore desirable to limit the magnitude of the torquetransferred to the reduced diameter section of drillpipe to preventdamage to the smaller pipe. As used herein, the term “torque” is used torefer to the turning force applied to an object measured inforce-distance units.

Prior downhole torque limiting systems utilized shear pins or otherelements which are designed to fail when a specified torque is exceeded,allowing the pipe sections to rotate with respect to each other. Toreset these devices, the drillstring was removed from the well and thefractured pin replaced. Requiring the device to be brought to thesurface is undesirable and expensive.

The apparatus of the present invention has an axial passageway and actsas a downhole torque limiter when connected between a driver and adriven member, such as, between two different size pipes. The presentinvention can be preset to disengage or slip when specified torquemagnitude is exceeded and will reset without requiring removal from thewell.

According to the methods of the present invention, the downhole torquelimiter is first set at the specified torque magnitude and thenconnected between a driver and a driven member, for example, twosections of drill pipe. The pipe is placed in the well and rotated withthe rotational force transmitted by the downhole torque limiter untilthe specified torque is exceeded. When a predetermined torque magnitudeis reached, the torque limiter will disengage and slip to allow relativerotation between the pipe sections and will remain disengaged until therotation is stopped or at least the rotation rate is reduced. Once therotation decreases, the torque limiter will reset without removing thetool from the well and, when rotation recommences, will transmitrotational force up to the specified torque magnitude.

BRIEF DESCRIPTION OF THE FIGURES

The advantages and features of the present invention can be understoodand appreciated by referring to the drawings of examples attachedhereto, in which:

FIG. 1 is an exemplary view of a tapered drillstring, showing thedownhole torque limiter of the present inventions connected to twosection of drill pipe;

FIG. 2A-E illustrates a longitudinal cross-sectional view of thedownhole torque limiter of the present inventions;

FIG. 3 is a cross sectional taken on line 3-3 of FIG. 2 looking in thedirection of the arrows;

FIG. 4 is a plan view partially in section of the lower mandrel of thetorque limiter of the present inventions;

FIG. 5 is a cross-section view taken on line 5-5 of FIG. 4, looking inthe direction of the arrows;

FIG. 6 is a longitudinal cross-section view of the lower mandrel of thetorque limiter of the present inventions;

FIG. 7 is a longitudinal cross section of the center mandrel of thedrill string clutch of the present inventions;

FIG. 8 is a cross-section view of the center mandrel of the drill stringclutch of the present inventions;

FIG. 9 is an exploded view of one embodiment of a piston assembly of thedrill string clutch of the present inventions;

FIG. 10 is an assembly view of another embodiment of a piston assemblyof the drill string clutch of the present inventions; and

FIG. 11 is an exploded view of another embodiment of a clutch pistonassembly illustrated in FIG. 10 of the drill string clutch of thepresent inventions.

DETAILED DESCRIPTION OF THE INVENTIONS

By reference to the drawings, wherein like or corresponding parts aredesignated by like or corresponding reference numbers throughout theseveral views, one of the presently preferred embodiments of theresettable downhole torque limiter will be described. This FIG. 1illustrates the torque limiter 300 in its typical orientation connectedin a drillstring located in the wellbore W. Drillpipe section designated“U” is the upper section and the section designated “L” is the lowersection. The terms “up” and “down” are used herein to refer to thedirections along the wellbore toward and away from the well head and notto gravitational directions. The term “tubing string” or “drillstring”or “drillpipe” are used herein to refer to coil tubing, tubing, drillpipe or other tool deployment strings. While the example selected forexplanation is drillpipe, the torque limiter of the present inventioncan be used with tubing, casing, downhole tools or any type of tubularmembers.

Torque limiter 300 has an upper driver end 302 and a lower driven end304. Typically, upper end 302 and lower end 304 have threadedconnections for making up torque limiter 300 within a tubular string,for example, a drillstring. A central bore B (not shown in FIG. 1)extends the length of torque limiter 300, to permit fluids to be pumpedthrough the tool and down the drillstring.

Driver end 302 is connected to upper section U by a threaded connection.In the illustrated example, the upper section U is connected to thesurface rig and can be raised, lowered and rotated thereby. Driven end304 is connected to the reduced diameter lower section L. As is typical,a smaller diameter wellbore casing can be present, necessitating the useof the reduced diameter lower section L to access the smaller diameterwellbore casing. In the illustrated embodiment, torque limiter 300connects upper U and lower L sections together and transmits rotationalmovement and torque to lower section L.

As will be explained in detail, torque limiter 300 can be set up toallow the driver end 302 and driven end 304 ends to slip with respect toeach other when the magnitude of the torque applied to torque limiter308 exceeds the preset limit. Thus, when the torque applied by adrilling rig while rotating upper section U exceeds a specified limittorque limiter 300 will allow you upper and lower ends to slip.According to a particular feature of the present invention, whenrotation of the upper section ceases or is reduced, torque limiter 300will reset to condition where the ends no longer slip with respect toeach other, and rotational movement and torque will transferred to lowersection L.

The details of the construction and operation of torque limiter 300 willbe described by reference to FIGS. 2A through 11. The major componentsof torque limiter 300 comprise: upper driver mandrel assembly 320; lowerdriven mandrel 340; inner sleeve 360; outer sleeve 380; first cup-shapedbody 402 and second piston assembly 420. Upper driver mandrel 320comprises upper mandrel 322 and upper mandrel extension 324 joinedtogether by threads T and sealed by an annular seal S. Connection meansC in the form of internal threads are located on the external end ofupper mandrel 322.

Inner sleeve 360 is mounted in upper mandrel extension 324 and formsgrooves 364 between upper mandrel extension 324 and inner sleeve 360.The inner sleeve 360 is actually made up of a plurality of annularsections 362 with annular seals S in the adjacent edges. Each annularsection 362 has at least one axially extending port 368 extendingtherethrough. Lower mandrel 340 extends into upper mandrel extension 324and inner sleeve 360 and forms an annular chamber 366. Packing P sealsthe annulus between the upper and lower mandrels. The upper mandrel 320is provided with a connection means C in the form of external threads onits external end. The connection means C on the upper and lower mandrelsaccommodate connection of torque limiter 300 to a drillstring or thelike.

As illustrated in FIG. 2B, bearing and race assemblies 326, located ininner sleeve 360, pivotally connect lower mandrel 340 to upper mandrelassembly 320. In the present embodiment, five separate ball bearing sets328 engage annular grooves 342 in reduced diameter portion 344 of lowermandrel 340 and act as multiple thrust bearings to transfer axial loadsbetween upper mandrel assembly 320 and lower mandrel 340. Suitable portsG are provided for inserting lubricant into chamber 366 and bearing raceassemblies 326. As illustrated in FIG. 2E, bearing race assemblies 326are hydraulically connected such that the thrust forces are balancedbetween ball bearing set 328. Each of the bearing race assembly 326 iscup shaped and comprises a pair of annular oppositely facing bearingraces 330 and 331 and an annular liner 332. In this view, the torquelimiter is loaded in axial tension with the ball bearings, contactingthe downward facing bearing races 330. It should be understood that whenin compression, the lower mandrel 340 will shift down from theillustrated position to place the ball bearings in contact the upwardfacing races 331. Race assemblies 326 are mounted to shift axiallybetween annular stops 370 on inner sleeve sections 362 as the loaddirection changes.

During assembly of the bearing system, grease is injected into and fillsgrooves 364. Grease also moves through ports 368 to fill in annularvoids 372 around liners 332. This system acts to balance the axial loadsamong the thrust bearing assemblies. Balancing is achieved by thebearing races 330 acting as axial pistons. Seal rings S seal betweensections 362. Sections 362 and annular liner 332 form annular chambersthat act as cylinders in which the bearing races travel. Because theannular chambers are in communication with one another through the ports368 in each outer sleeve 362 and the grooves(s) 364, the force exertedby one ball set on its outer races 330 and 331 is transmitted to theother outer races, which move to exert the force on their restraint. Theraces facing the same direction will be restrained by the ball bearingsand transmit the load to the lower mandrel 340, effectively sharing itin this reaction. The races facing the opposite direction will berestrained by a shoulder. This is true for both load directions. Somemovement of the mandrel 340 is required to change load direction, andensure the bearing balls cannot be locked by opposing outer racesengaging simultaneously due to assembly dimensional variation. The axialforce is therefore shared by all bearing races in one direction. Thiseliminates the typical problem of precision shimming axial bearing setsto attempt load sharing, and the inherent problems in assembling bearingsets in a challengingly small space.

In FIGS. 2C and 3, outer sleeve 380 is illustrated mounted around uppermandrel extension 324 to form an annular chamber 336 there between. Grubscrews 338 carried by upper mandrel extension 324 engage outer sleeve380 to fix it into position. Suitable seals S close off the ends ofannular chamber 336.

As illustrated in FIGS. 2C, 3, 7 and 8, upper mandrel extension 324 hasa plurality of radially extending bores 334. In the illustratedembodiment, twelve separate bores 334 (four sets of three) are present.The individual bores in each set are circumferentially spaced, onehundred and twenty degrees apart with adjacent sets offset by sixtydegrees.

Radially movable piston assemblies 400 and 420 are mounted toreciprocate in bores 334. In the illustrated embodiment, eleven firstpiston assemblies 400 and one second piston assembly 420 are mounted inthe twelve bores 334. However, the number of bores and mix of pistonassemblies can be varied according to the anticipated loads on thetorque limiter.

In FIGS. 3, 4 and 5, lower mandrel 340 has contact surfaces 346separated by ridges 350 formed thereon and positioned to be adjacent toradially extending bores 334. Contact surfaces 346 define chambers 348inside upper mandrel extension 324. In this embodiment, six axiallyextending contact surfaces 346, circumferentially spaced sixty degreesapart, are present on lower mandrel 340. As will be described in detail,when the piston assembly 400 and 402 are in the engaged positions, theywill contact surfaces 346 to transfer rotational movement and torsionalforces between upper and lower mandrels. Piston assemblies 400 and 420are illustrated in the Figures in the engaged position. When pistons arein the disengaged position (retracted from the contact surfaces), upperand lower mandrels are uncoupled and can rotate with respect to eachother.

The structural details of piston assembly 400 are illustrated in FIG. 9.Piston assembly 400 comprises: body 402, a plurality of Bellevillesprings 404, mushroom-shaped spring follower 406, and annular seal 408.A contact surface 410 is formed on body 402. Annular seal 408 will sealwith internal wall bores 334. When piston assemblies 400 are installedin bores 334, Belleville springs 404 will resiliently urge body 402apart from spring follower 406.

As illustrated in FIGS. 2C and 3, the action of Belleville springs 404will resiliently urge or force contact surface 410 on body 402 in adirection to contact one of the contact surfaces 346 on lower mandrel340. The mushroom-shaped spring follower 406 engages the inner surfaceof outer sleeve 380. As will be explained in more detail hereinafter,hydraulic fluid fills annular chamber 336, bores 334 and chambers 348.Piston assemblies 400 and 420 are hydraulically locked in position bythe hydraulic fluid. As the hydraulic fluid moves between chambers 336and 348, contact surface 410 will move into and out of engagement withlower mandrel 340. As used herein the term “hydraulically locked” isused to refer to the condition where a piston or other item is held inposition against movement in a cylinder or chamber by a fluid.

The structural details of piston assembly 420 are illustrated in FIGS.10 and 11. Piston assembly 420 comprises a body 422, Belleville springs424, cap 426, seat 430, ball valve 432, and spring 434. Body 422 has anannular seal 434 for sealing against the interior walls of bore 334. Cap426 has external threads T which engage internal threads T in body 422.When cap 426 is threaded into body 422, Belleville springs 424 will becompressed. An annular seal S is mounted in bore 428 of cap 426. Hollowpin 440 is threaded into body 422 and extends into the assembly towardbore 428. The axial position of the pin can be adjusted by threading thepin into or out of the body. Ports 442 formed in contact surface 423 ofbody 422. Ball valve 432 is mounted in seat 430 and is held in seat 430blocking port 431 by an assembly of spring 434, support 436 and snapring 438. As is illustrated in FIG. 10, when assembled ball 432 blocksport 431, and is positioned adjacent to pin 440. When the pressuredifferential across seat 430 compresses Belleville springs 424, seat 430moves toward pin 440 to dislodge ball 432, allowing fluid pressure toequalize across piston assembly 420.

As illustrated in FIGS. 2C and 3, the action of Belleville springs 424will resiliently urge or force contact surface 423 on body 422 in adirection toward the engaged position, contacting one of the contactsurfaces 346 on lower mandrel 340. Seat 430 will engage Bellevillesprings 424 and the inner surface of outer sleeve 380. When the forcegenerated by differential hydraulic fluid pressure acting across seat430 exceeds the force exerted by springs 424, seat 430 will tend to movetoward pin 440. If enough pressure force is exerted, seat 430 will moveto a point where ball 432 contacts pin 440 and is dislodged from port431. With the ball dislodged, hydraulic lock of the piston is removed byfluid leaking or flowing from annular chamber 336 into chambers 348,allowing piston assembly 420 to move away from contact surfaces 346 tothe disengaged position. It is also essential to note that the travel ofthe piston will act on the valve by the pin moving up against the ball.As such, slight movement of the seat (having attained the reliefpressure) opens the valve and holds it open, making the easy outwardmovement of all pistons possible. Second, the restricted flow paththrough piston assembly 420 means that, for example, at speeds aboveapproximately seven rpm the pistons do not travel back “down” far enoughto allow re-seating of the ball. As the piston 420 engages the ridges350, slight pumping will occur. There is no substantial pressuredifferential across the pistons other than that created by the inherentflow restriction in piston 420 and so a minimal heat buildup andtorsional resistance.

It should be noted that the number and rating of the Belleville springswill be proportional to the torque magnitude at which the torque limiterwill disengage and allow the upper and lower mandrels to slip (rotatewith respect to each other). Accordingly, the torque limiter can bepreset to slip or disengage at a torque magnitude related to the tubingstring or tool attached to the lower mandrel by adjusting the number andrating of the Belleville springs and adjusting the axial position of thepin. Also note that the axial position of pin 440 in the body 422 isadjustable. By turning the pin-screw assembly and extending the travelof the seat 430 needed before the ball is unseated, a higher hydraulicpressure (and therefore torque) is required to compress the Bellevillesprings this greater distance. An appreciable amount of torque variationis hereby attained.

The method of using the torque limiter of the present inventioncomprises first assembling the torque limiter with the proper Bellevillesprings and pin 440 adjusted to set the specified torque magnituderequired to be transmitted by the device. Moving the pistons 400 and 420to the engaged position with the piston surfaces 410 and 423 contactingsurfaces 346 on the lower mandrel 340 and the pistons hydraulicallylocked in the engaged position. Assembling the torque limiter in atubing string and lowering the tubing string into a subterraneanwellbore. Rotating the tubing string while the torque limiter is in theengaged position and utilizing the torque limiter to transmit torquethrough the device up to the specified torque magnitude. Rotating theupper or driver mandrel assembly 320 while engaging the pistonassemblies 400 and 420 with the contact surfaces 346 transmits torqueand rotational movement to the lower driven mandrel 340.

Next, moving the pistons 400 and 420 from the engaged position to thedisengaged position when a specified torque magnitude is exceeded. Thepistons are moved to the disengaged position when fluid pressure inannular chamber 336 is relieved by engaging the ball valve 432 with thepin 440 whereby the ball is moved away from the seat 430 venting fluidfrom annular chamber 336. Venting fluid across piston 420 will removethe hydraulic lock and allow all the pistons to move away from the lowermandrels contact surfaces 346. With the pistons in the disengagedposition, the upper and lower mandrels are free to rotate with respectto each other. As the pistons rotate in the disengaged position, thecontact surfaces 410 and 423 will engage ridges 350 on the lower mandrel340 and be prevented from returning to the engaged position untilrelative rotation between the upper and lower mandrel ceases or issubstantially reduced in rate.

To reset the torque limiter to the engaged position, the pistons must bepermitted to return to a position where they engage contact surfaces 346and are hydraulically locked in place. For example, once relativerotation this ceases, the force of the Belleville Springs will cause thecontact surfaces on the pistons to move into engagement with the lowermandrel's contact surfaces 346. During this piston movement, hydraulicfluid flows from chamber 348 through piston 420 and into annular chamber336. It should be appreciated that the process of resetting the torquelimiter, by moving the pistons moving the pistons back into the engagedin disengaged position, can be repeated as many times as necessary whena specified torque magnitude is exceeded.

Materials

It is to be understood, as known to those of ordinary skill in therelevant art field, that the torque limiter would further comprisevarious seal and bearing elements, certain of which are shown in theaccompanying drawings. Also, torque limiter 300 may be made of suitablematerials well known to those of ordinary skill in the relevant art,such as high strength steel alloys, resilient parts for seals, etc.

While the preceding description contains many specificities, it is to beunderstood that same are presented only to describe some of thepresently preferred embodiments of the invention, and not by way oflimitation. Changes can be made to various aspects of the invention,without departing from the scope thereof. For example, dimensions andmaterials can be changed to suit particular situations; the torquelimiter can be run in conjunction with other apparatus; and variousmethods of use of the downhole clutch may be employed.

Therefore, the scope of the invention is not to be limited to theillustrative examples set forth above, but encompasses modificationswhich may become apparent to those of ordinary skill in the relevantart.

1-4. (canceled)
 5. A bearing assembly, comprising: a first membertelescoped into a tubular member to form an annulus therebetween; atleast two axially spaced sets of bearings mounted in the annulus inannular grooves in one of the members; at least two bearing racesslidably mounted on the other member positioned to engage the at leasttwo axially spaced sets of bearings; and hydraulically coupling thebearing races.
 6. The bearing assembly of claim 5, wherein the at leasttwo bearing races travel axially within the annulus.
 7. The bearingassembly of claim 6, wherein hydraulically coupling comprises thebearing races being in fluid communication.
 8. The bearing assembly ofclaim 5, wherein each of the at least two bearing races comprises a pairof annular oppositely facing bearing race elements.
 9. The bearingassembly of claim 8, wherein each bearing race comprises a surfaceshaped to mate with at least one of the bearing sets.
 10. The bearingassembly of claim 9, wherein each race element is partially concave. 11.The bearing assembly of claim 5, wherein at least one of the bearingsets comprise spherical bearings.
 12. The bearing assembly of claim 5,wherein at least one of the annular grooves is partially concave. 13.The bearing assembly of claim 6, wherein the annulus further comprisesan inner sleeve in the tubular member that includes inner sleevesections and annular liners in which the bearing races are slidablymounted.
 14. A bearing assembly, comprising: first and second memberstelescoped together to form an annulus therebetween; at least twoaxially spaced bearing assemblies mounted in the annulus to connect themembers to rotate with respect to each other; each bearing assemblycomprising a plurality of spherical balls, an annular groove in one ofthe members, the groove engaging the balls; a bearing race mounted onthe other member to move axially with respect to another member, therace engaging the balls; and a hydraulic piston reciprocally mounted ina chamber connected to the second member holding the bearing race inaxial position with respect to the second member; and the piston axiallypositioning the bearing races being connected in fluid communication.15. The bearing assembly of claim 14, wherein each bearing racecomprises a pair of oppositely facing bearing race elements.
 16. Thebearing assembly of claim 15, wherein the similarly facing race elementsof each bearing race the elements move in the same axial direction. 17.A method of balancing an axial load in a tubing string at a subterraneanlocation in a well, comprising: forming the bearing assembly of claim 5in a tubing string, wherein the at least two bearing races travelaxially within the annulus; generating an axial load within the tubingstring; and transferring an axial load from one bearing race to at leastone other bearing race.
 18. The method of claim 17, wherein the axialload is transferred through the hydraulic coupling of the bearing races.19. The method of claim 18, wherein the axial load is shared by thebearing races in one direction.
 20. The method of claim 18, wherein eachbearing race comprises a pair of annular oppositely facing bearing raceelements, each race element having a surface shaped to mate with atleast one set of bearings.
 21. The method of claim 20, wherein each raceelement facing the same axial direction is restrained by the bearingsand transmits the axial load to the first member.
 22. The method ofclaim 20, wherein each race element facing the opposite axial directionis restrained by an annular stop on the tubular member.
 23. The methodof claim 20, wherein the bearing race elements are at least partiallyconcave.
 24. The method of claim 20, the at least one set of bearingswherein the bearings are spherical.